versioner: Port to clang-r344140

This commit updates bionic versioner to use clang-r344140.  To be
specific, this commit renames `clang::vfs::FileSystem` to
`llvm::vfs::FileSystem` and updates the headers.

Bug: 111759196
Test: bionic/tools/versioner/run_tests.py
Change-Id: I304ecae79da5a1638ae755dac92b52e314019cf1
diff --git a/tools/versioner/src/VFS.h b/tools/versioner/src/VFS.h
index e2ab002..e4aac75 100644
--- a/tools/versioner/src/VFS.h
+++ b/tools/versioner/src/VFS.h
@@ -20,8 +20,8 @@
 #include <string>
 
 #include <llvm/ADT/IntrusiveRefCntPtr.h>
-#include <clang/Basic/VirtualFileSystem.h>
+#include <llvm/Support/VirtualFileSystem.h>
 
-llvm::IntrusiveRefCntPtr<clang::vfs::FileSystem> createCommonVFS(const std::string& header_dir,
-                                                                 const std::string& dependency_dir,
-                                                                 bool add_versioning_header);
+llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> createCommonVFS(const std::string& header_dir,
+                                                                const std::string& dependency_dir,
+                                                                bool add_versioning_header);